The process of megakaryocytopoiesis is initiated with the terminal commitment of pluripotent hematopoietic stem cells (HSCs) into a differentiation pathway that results in the production of mature platelets into the circulation (Ellis, M. H. et al. Blood, 9:1-6 (1995). The events involve megakaryocyte proliferation followed by megakaryocyte maturation into platelets, and these processes are regulated by a number of cytokines with specific megakaryocytic maturational activity and a variety of cell adhesive interactions.
Factors known to support and regulate megakaryocyte growth and development include megakaryocyte growth and development factor and cytokines (Bertolini, F. et al. Blood, 89(8):2679-2688 (1997); Nagahisa, H. et al. Blood, 87(4):1309-1316 (1996)); and bone marrow stromal cells (Guerriero, A. et al. Blood, 90(9):3444-3455 (1997)). A process which would facilitate the development and maturation of megakaryocytes into platelets which does not require the use of exogenous factors would be invaluable since the time to platelet recovery following bone marrow or peripheral blood progenitor transplantation can be very protracted.